The invention relates to a microscope having at least one beam path and an optical system along an optical axis, and having a fade-in element for reflecting in image information for an observer's eye. Microscopes in the sense of the invention are to be understood principally, but not exclusively, as devices which have a main objective, a tube and an eyepiece for looking into. In the widest understanding of the invention, therefore, all other optically magnifying devices are to be understood which are directed onto an object to be magnified and make visible to the observer's eye a magnified image of the object observed. Microscopes, in particular stereomicroscopes, for example surgical microscopes, in particular also video (stereo)microscopes which are connected to an electronic data processing unit and/or a display are comfortable for a user when the latter is not exclusively dependent on the image currently seen through the main objective of the microscope, but also obtains when looking into the tube of the microscope additional information which is generally superimposed on the currently seen image. This can be graphic characters, symbolic representations, marks, but also superimposed images of the same object which are obtained, for example, with the aid of image processing software from the currently seen object or by means of other visualizing measures (for example X-ray pictures, CT etc.) from the same object. Microscopes with fade-in possibilities or image superimposition possibilities are also used, inter alia, in technology, for example materials engineering, material analysis, silicon technology criminology, etc., but also, in particular, in medicine for diagnosis, serological examinations, during operations etc.
Chiefly in the case of surgical microscopes and, in particular, during an operation, a quantity of information arises which can be of great importance to the surgeon. This is, for example, information on the patient or his state of health or patient parameters such as pulse, blood, pressure, oxygen content of the blood etc. These are in addition to the currently observed superimposing images, for example, information on specific parameters of the microscope, information on the position of the observed operation zone, as well as control data which, for example, the surgeon delivers at will via control elements such as computer mouse or foot switch to the data processing device or to control elements for the microscope, in order to control the latter as required, for example to focus it, etc.
The use of the invention in the field of surgical microscopy will be taken up below by way of example. The invention is also applicable in other fields.
Surgical microscopes are used by the operating surgeon for optical magnification of the operation zone. Operation technology is so far advanced in this connection that magnifications in the region of 50 fold and above are no rarity. It is important during an operation that the all important information is transmitted to the operating surgeon as quickly and unambiguously as possible, in order for him to be able to conclude the operation in as short a time as possible. Since the operating surgeon preferably removes his eyes as little as possible from the eyepiece of the surgical microscope, and, conversely, difficulties of comprehension can be expected with the spoken word, it is obvious for important information such as, for example, patient data, micoscope control data or positional data to be rendered visible in the tube.
This is achieved according to known techniques by representing the relevant information on a display and reflecting the image of this display into the tube via a beam splitter. Because the user always wants a good light yield for the object observed, which can frequently be ensured by high illumination densities at the object, the problem of adequate optical density of the image reflected in or superimposed often arises in the case of reflecting in. In this case, tube displays (CRT) frequently provide no way out. The use of LCDs with strong background illuminations is; attended by disadvantages in the field of resolution and also in attempting to reproduce thin lines, also since the pixel width of the LCDs is relatively large, and therefore relatively wide minimum line thicknesses are prescribed. Moreover, LCD pixels form rasters which can produce problems with edge definition and resolution.
If it is now desired, for example, to have edge improvements, image colorings, contrast improvements or other marks which are as thin as possible, and which have been prepared, for example, after prior recording by means of video technology and by means of electronic image processing, it can happen disadvantageously that the known possibilities produce unsatisfactory performance with regard to brightness and/or line thickness. Contouring would be desirable, but not: achievable optimally using the means of the prior art.
A special field for the superimposition of images rises, for example, in the application of computer tomography (CT) or magnetic resonance imaging (MRI) in conjunction with stereomicroscopy. Data are obtained from CT and MRI in order to obtain a sectional image of the zone of interest from the patient which, in the final analysis after EDP, permits the representation on a computer monitor (stereo display screen) of a three-dimensional model which is faithful to reality. By using such three-dimensional images, the attending doctors are better able to localize the type and spread of the diseased area. However, it is frequently the case that both the image currently seen and the available three-dimensional representation of X-ray or CT image data are not clear enough for the relevant area to be identified during operation in a marked-off fashion with sufficient clarity from the remaining region.
As already mentioned, contour reworking or contour representation suffice for this identification to be performed optimally, but these are to be as bright and thin as possible in order not to cover other details.
Accomplishing this is one of the main objects on which the invention is based.